Canadian Application Publication

Title (French)

Abstract (English)

The present invention provides a apparatus as an after-market, upgrade kit constructed and arranged to be installed onto an coupled snowmobile suspension system that, when installed, provides for quick and easily accessible coupling adjustment. Specifically, the upgrade kit of the present invention is configured to be installed onto the Polaris® line of snowmobiles. The upgrade kit includes a shaft having an axis of rotation, a pair of coupling blocks, and an indexer plate. The coupling blocks are adapted to be fixedly connected relative to the axis of rotation at each end of the shaft so that a torque in the shaft will be transmitted to the coupling blocks. The coupling blocks have a plurality of sides corresponding to a plurality of positions of the coupling blocks, each of the sides being located at a different distance from the axis of the shaft when the coupling blocks are connected to the shaft. The indexer plate is adapted to engage one of the coupling blocks at a selected positions of the coupling blocks. The shaft is constructed and arranged to be mounted between a longitudinal pair of slide rails of the snowmobile suspension with two bolts, and the coupling blocks are adapted to be rotated about the axis to thereby adjust the coupling of the snowmobile. A pair of support brackets are attached on the outside of the slide rails to the shaft to pass forces seen by the coupling blocks to the slide rails. Adjustment of the coupling blocks is accomplished by applying a torque to one of the bolts in a direction which tightens the bolt.

CA 02358154 2001-10-03 ADJUSTABLE APPARATUS AND KIT FOR A COUPLED SNOWMOBILE SUSPENSION Field of the InventionThis invention relates to snowmobile suspension systems, and more particularly to coupledsuspension systems, and even more particularly to an apparatus, in the form of an after-marketupgrade kit, that permits, when installed, quick and easily accessible coupling adjustment. Background of the InventionTracked vehicles such as snowmobiles have rear suspension systems generally consisting offront and rear suspension arms pivotally mounted on shafts, which are rotatably connected to theframe of the snowmobile, and a slide frame, which comprises a pair of laterally spaced apart sliderails or longitudinal skids interconnected transversely on opposing lateral sides of the machine. Theslide rails are in sliding contact with an endless belt which provides ice and snow surface contactand a friction drive for the snowmobile. In many current arrangements, front and rear suspensionarms pivotally interconnect the chassis to the slide frame.It is generally known in the art that independent movement of the front and rear suspensionarms is less desirable than a suspension system in which the front and rear suspension arms arecoupled. In an uncoupled suspension system, when the front suspension arm deflects as it contacts abump, the independent rear suspension arm remains in its ride or fully extended position. Thisresults in an angle of incidence between the slide rails and the bump. Unless the impact is so largethat it compresses the rear suspension arm spring and shock absorber assembly, thereby flattening1

CA 02358154 2001-10-03the angle of incidence, the slide rails will act as a ramp forcing the rear of the snowmobile upward.That is, with the slide rails angled in an upward incline due to the independent deflection of thefront suspension arm, but not the rear suspension arm, the snowmobile will hop over the bump,imparting a secondary jolt which increases in intensity with the speed of the snowmobile. Thissecondary jolt also results in a loss of control and a reduction of the speed of the snowmobile.On the other hand, a coupled suspension system is one in which, for example, the rearportion of the suspension system reacts (i.e., is coupled) to the compression experienced by the frontportion of the suspension system as the snowmobile passes over a bump in the terrain. In effect, thebump is « communicated » to the rear portion of the suspension, causing the rear portion to be pulledupward toward the chassis before the rear portion actually reaches the bump. This reduces the angleof incidence between the slide rail and the bump, which thereby reduces the secondary joltexperienced by the rider. As a result, a coupled suspension system provides for an improved ridebecause the coupled suspension is better suited to adjust to varying terrain conditions.Manufacturers have developed a variety of ways to provide coupled suspension systems,which typically involve restricting the amount of longitudinal movement of the rear suspension arm.Such systems are shown in U.S. Patents Nos. 5,881,834, 5,692,579, 5,667,031, and 5,944,134.The suspension system disclosed in Polaris’ 5,692,579 (« ‘579 ») patent is shown in Figs. 1-4,where Fig. 1 shows the overall suspension system removed from the snowmobile, and Figs. 2-4show the design approach used to couple the suspension system. As disclosed in the ‘579 patent anddepicted in Figs. 2 and 4, the linkage of the rear suspension arm 20 with the lower pivot arm 26permits the front of the slide rails 10 to rise substantially independently of the rear portion of sliderails. During this independent movement of the front portion of the suspension, the lower pivot arm26 pivots from the rearward position shown in solid lines in FIG. 2 to the forward position depicted

2

CA 02358154 2001-10-03in broken lines. At the point which the front surface 27 of the lower pivot arm 26 engages the frontadjuster block 30, further independent upward movement of the front end of the suspension isprevented. That is; further upward movement of the front of the slide rails 10 is mechanically linkedthrough the adjuster block 30 to the rear suspension arm 20, causing upward movement of the rearof the suspension (the rate of upward movement of the rear of the suspension may or may not beequal to the rate of movement of the front of the suspension, depending on the specific geometricconfiguration of the system).The degree of independent movement afforded to the front of the suspension rails 10 isdependent on the distance between the rear stop 32 and the front adjuster block 30 in comparison tothe width of the lower pivot arm 26. The rear surface 31 of the front adjuster block 30 thus providesa limit on the relative forward movement of the lower end of the suspension arm 20 with respect tothe slide rail 10.The Polaris~ system of the ‘579 patent further provides variability to the position of thislimit, thereby giving the rider some control over the performance characteristics of the suspension.This variability is provided by using rectangular adjuster block 30, which has four surfaces that areeach positioned at varying distances from the block’s central mounting point, as indicated bydistances « dl » through « d4 » in Fig. 4. By rotating the block to select one of the surfaces, theposition of the limit with respect to the lower end of the suspension arm 20 can be controlled.However, with the above Polaris~ system, it is difficult for the rider to make a desiredadjustment to the adjuster block 30, especially when the rider is in the field. To make anadjustment, the rider must first loosen the central mounting point (a bolt). Then, the rider mustmanage to rotate adjuster block 30, either with his fingers or with the aid of another tool, to the

3

CA 02358154 2001-10-03desired location, and then retighten the central mounting point. The rider must then repeat thesesteps for the adjuster block on the opposite side of the slide rail. Considering that the rider maywish to make such adjustments while in the field, where he/she would encounter other obstacles,such as deep snow, cold weather, and generally unfavorable conditions for handling tools andequipment, it is apparent that making such adjustments to the adjustable block 30 in order tocompensate for differing terrain conditions is difficult with the above Polaris~ system.It is therefore the object of this invention to provide an apparatus, in the form of an after-market upgrade kit, for installation onto a coupled snowmobile suspension system of the kinddescribed in Patent No. 5,692,579 that, when installed, allows for a quick and easy adjustment of thefront to rear coupling.It is further an object of the present invention to provide an apparatus, in the form of anafter-market upgrade kit, specifically configured to be installed onto the Polaris~ line ofsnowmobiles. Summary of the InventionIt is the object of the present invention, therefore, to provide an apparatus and an after-market upgrade kit constructed and arranged to be installed onto a coupled snowmobile suspension.The upgrade kit includes a shaft having an axis of rotation, a pair of coupling blocks, and an indexerplate. The coupling blocks are adapted to be fixedly connected relative to the axis of rotation ateach end of the shaft so that a torque in the shaft will be transmitted to the coupling blocks. Thecoupling blocks have a plurality of sides corresponding to a plurality of positions of the coupling

4

CA 02358154 2001-10-03blocks, each of the sides being located at a different distance from the axis of the shaft when thecoupling blocks are connected to the shaft. The indexer plate is adapted to engage one of thecoupling blocks at a selected positions of the coupling blocks. The shaft is constructed andarranged to be mounted between a longitudinal pair of slide rails of the snowmobile suspension, andthe coupling blocks are adapted to be rotated about the axis to thereby adjust the coupling of thesnowmobile.Other obj ects and advantages of the present invention will be realized in accordance with thefollowing detailed description, appended drawings, and claims. Brief Description of the DrawingsThe various embodiments of the present invention are shown throughout the drawings, inwhich:Fig. 1 is a perspective view of a coupled snowmobile suspension of the prior art; Fig. 2 is a plan view of Fig. 1, and also shows the coupling apparatus; Fig. 3 is an enlarged view of the coupling apparatus of Fig. 2;Fig. 4 is an enlarged view of the coupling block of Figs. 2 and 3 of the prior art;Fig. 5 is a perspective view of the preferred embodiment of the apparatus of the presentinvention showing the assembly thereof before attachment to the snowmobile suspension;Fig. 6 is a plan view of the shaft of the upgrade kit of the preferred embodiment;Fig. 6B is a section view of the rectangular portions of the main shaft of Fig. 6;Fig. 6C is a plan view of a second embodiment of the main shaft, where the coupling blocksare integrally formed with the main shaft;Fig. 7 is a plan view of a coupler block of the upgrade kit of the preferred embodiment;

CA 02358154 2001-10-03Fig. 8 is a side view of a coupler block of the upgrade kit of the preferred embodiment; Fig. 9 is the plan view of Fig. 7 showing dimensional attributes;Fig. 10 is a perspective view of a coupling block having mounted thereto a ball springplunger, which is the preferred embodiment of a protrusion of the upgrade kit; Fig. 11 is a side view of Fig. 10;Fig. 12 is a side view of a coupling block having mounted thereto a second embodiment of aprotrusion mounted to a coupling block;Fig. 13 is a side view of a coupling block having mounted thereto a third embodiment of aprotrusion mounted to a coupling block;Fig. 13B is a perspective view of a second embodiment of the indexer plate and couplingblocks, where the indexer plate has mounted thereto the protrusions of Figs. 11, 12, 13, and thecoupling block includes a plurality of depressions;Fig. 14 is a plan view of the indexer plate of the upgrade kit of the preferred embodiment;Fig. 15 is a plan view of a support plate of the upgrade kit of the preferred embodiment;Fig. 16 is a plan view of a Polaris~ XTR.A-10 snowmobile suspension system without theupgrade kit installed; Fig. 17 is an enlarged view of the coupling portion of Fig. 16;Fig. 18 is a plan view of a portion of the suspension system of Fig. 16 with the upgrade kitinstalled;Fig. 19 is a top view of the upgrade kit installed onto the Polaris~ XTRA -10 snowmobilesuspension system of Fig. 16; andFig. 20 is a depiction of the position of the lower arm engaged with a coupler block in twodifferent positions of the coupler block.6

CA 02358154 2001-10-03 Fig. 21 is a snowmobile comprising the upgrade kit of the present invention. Detailed DescriptionReferring now more particularly to the Figures, wherein like reference numbers are used forlike components where applicable, the apparatus of the present invention, which is also referred toas an upgrade kit, is generally indicated at 40 and is illustrated in Fig. 5. Generally, the upgrade kit40 is constructed and arranged to be installed onto an adjustably coupled, snowmobile suspensionsystem, so that when installed, the adjustment of the coupling is made quicker and easier. Morespecifically, the upgrade kit 40 is configured to be assembled onto the Polaris~ line of snowmobilesthat are originally manufactured with an adjustable, coupled suspension systems, as described abovewith reference to Figs. 1-4.Refernng to the Fig. 5, the upgrade kit 40 comprises, among other components, a shaft 42,two adjustable coupling blocks 46, 48, an indexer plate 50, two bolts 54, 58, and two plate brackets62 & 66. Figure 5 shows the upgrade kit 40 as an assembly, but not installed onto the suspensionsystem, and Figs. 6-1 S show each component separately. The adjustable coupling blocks 46, 48 arehereinafter referred to as the coupling blocks 46, 48, and shaft 42 is also referred to as the mainshaft 42.As seen in Figs. 5 and 6, the main shaft 42 comprises a cylindrical portion 68 and tworectangular portions 70, 72 mounted at each end of the main shaft 42. The axis of the main shaft 42is designated as reference numeral 74. The corners of the rectangular portions 70, 72 preferablyinclude longitudinal chamfers 76 that extend a length L3 from the end of the main shaft 42, whichare configured to accommodate the coupling blocks 46, 48, described below. Each end of the main7

CA 02358154 2001-10-03shaft 42 has a threaded bore 78 formed to a depth of length L3 therein. The threaded bores 78accommodate bolts 54 and 58 in order to mount the upgrade kit 40 to the snowmobile suspension.The rectangular portions 70, 72 and cylindrical portion 68 of the main shaft are preferablyintegrally formed with the cylindrical portion 68 of the main shaft 42, and is preferably machinedfrom a single piece of machine stock. Of course, the main shaft 42 may be formed from othermanufacturing techniques, such as by a casting, or the rectangular portions 70, 72 can be separatelyformed and welded or otherwise connected to the cylindrical portion 68 to form main shaft 42.Also, the entire main shaft 42 may be rectangular, and the cylindrical portion 68 need not bepresent. In the preferred embodiment, the main shaft 42 is made of aluminum. However, it iscontemplated that any other suitable material can be used, as long as the material selected issufficiently strong and rigid.Each coupling block 46, 48, shown separately in Fig. 7, is a generally rectangularly-shaped,rigid structure and includes a generally rectangular bore 80. The dimensions of the rectangular bore80 are substantially the same as the dimensions of the rectangular portions 70, 72 of the main shaft42, such that the rectangular portions 70, 72 therein can be matingly inserted. The rectangularportions 70, 72, therefore, transmit torque from the main shaft 42 to the two adjuster couplingblocks 46, 48 during rotation of the main shaft. The axis 74 of main shaft 42, when inserted intocoupling blocks 46, 48, is coincident with the centers of the rectangular bores 80. The corners ofthe rectangular bore 80 are, preferably, fillet radiused in a size to prevent interference with thechamfers 76 of the rectangular portions 70, 72. Also, the outside corners of each coupling block 46,48 are preferably rounded with radii Rl, R2, R3, and R4 to facilitate rotation of the blocks.Although in the preferred embodiment the adjuster coupling blocks 46, 48 are separatestructures from the main shaft 42, it is also contemplated that the adjuster coupling blocks 46, 488

CA 02358154 2001-10-03may be integrally formed with the main shaft 42 (see Fig. 6C). That is, the main shaft 42 wouldcomprise coupler blocks 46, 48 integrally formed at each end of the main shaft. In such case, therectangular portions 70, 72 for transmitting torque to the coupling blocks would not be required.Whether integrally formed or as a separate structure, each coupler block 46, 48 in thepreferred embodiment includes a plurality of sides corresponding to a plurality of positions of thecoupling blocks. In the preferred embodiment, the coupling blocks 46, 48 include four sides 84, 85,86, 87 that are each located at a different distance from the axis 74 when the coupling blocks areconnected to the main shaft 42. As shown in Fig. 9 for clarity, each side 84, 85, 86, and 87 islocated a distance « d5 », « d6 », « d7 », and « d8 », respectively, from the center rectangular bore 80 (or,equivalently, the axis 74 of the main shaft 42). Adjustment of the coupling system after the upgradekit 40 is installed onto the snowmobile suspension system is accomplished by rotating the couplingblocks 46, 48 so that the desired side is selected for use (i.e., to engage surface 27 of lower pivotarm 26, shown in Fig. 3), which is discussed in detail below.In the preferred embodiment where the coupling blocks are separate structures from themain shaft, the adjuster blocks 46, 48 are made of ultra high molecular weight (UHMW) plastic,which is chosen for its light weight but high strength, rigidity, and superior wear characteristics.However, it will be understood to those skilled in the art that other suitable materials could also beused, such as steel alloy. If the coupling blocks are integrally formed with the main shaft 42, then,of course, the coupling block material would be the same as the main shaft material.In the preferred embodiment, at least one of the coupling blocks 46, 48 includes a cylindricalbore 82 formed therethrough, and a ball spring plunger 90 is inserted therein, as shown in Figs. 10and 11. The ball spring plunger 90 acts as an index stopping « pointer » or protrusion for indexing thecoupling blocks 46, 48 at a selected position in conjunction with indexer plate 50, which will be9

CA 02358154 2001-10-03described below. The ball spring plunger 90 is of the conventional type, and generally includes aprotrusion or ball 96 resiliently disposed, by a spring 97, against an interior edge of flange stop 94.The spring 97 is disposed within a cylindrical chamber defined by cylindrical walls 92, the diameterof which is slightly larger than the rectangular bore 80 so that the ball spring plunger 90interferingly fits within bore 80.Although a ball spring plunger 90 is used in the preferred embodiment, it will be understoodby those skilled in the art that other mechanisms can also be used to perform indexing of couplingblocks 46, 48, such as, for example, a resilient cantilever spring 98 formed with a protrusion or ball99, shown in Fig. 12, or a bevel spring 100 formed with a protrusion or ball 101, as shown in Fig.13.Indexer plate 50, shown separately in Fig. 14, has a through-hole 106 formed therethrough atone end and a through-hole 108 formed therethrough at its other end, which is also locatedapproximately centrally of a generally circular portion 110 of indexer plate 50. Four equallyspaced-apart through bores 112, 114, 116, 118 are formed toward the periphery of circular portion110 in surrounding location of through-hole 108, and all the holes are located at the same radialdistance from the center of through-hole 108. When the upgrade kit is installed onto thesnowmobile, through-hole 108 receives bolt 54 for positioning the indexer plate 50 relative to thecoupling blocks (bolt 54, along with bolt 58, also pivotally mounts the main shaft 42 to the sliderai1s10), and one of the holes (i.e., either bore 112, 114, 116, or 118) is aligned and engaged with theball spring plunger 90 to establish a position of the coupling blocks 46, 48. Through-holes 112,114, 116, and 118 may also be depressions in the indexer plate of sufficient size to sufficientlyengage the protrusion or ball 96 of the ball spring plunger 90. The other end of indexer plate 50 isbolted via through-hole 106 to the slide rail 10 of the snowmobile to thereby fixedly define the

CA 02358154 2001-10-03position of the four holes 112, 114, 116, 118 with respect to the coupling blocks 46, 48. Thedistance between the center of holes 106 and 108 is designated as L11. The indexer plate 50 ispreferably made of brass plate having a thickness of 0.074 inches. However, any other suitablematerial and appropriate thickness could also be used.Although in the preferred embodiment a protrusion is mounted to one of the coupling blocksfor engagement with a depression (or hole) of the indexer plate, it is contemplated that the indexerplate 50, rather than the coupling blocks 46, 48, may mount the protrusions. That is, as shown inFig. 13B, the ball spring plunger 90 may be mounted to indexer plate 50 for engagement with aplurality of depressions or bores 109 formed in one of the coupling blocks (see Fig. 13B).Each plate bracket 62, 66, shown separately in Fig. 15, defines two through-holes 122, 124formed therethrough at each end therein. The size and proximity of the through-holes 122, 124correspond with the through-holes 106, 108 of indexer plate 50. Thus, the distance, L12, betweenthrough-holes 122 and 124 is substantially the same as the distance L11. Through-hole 124 of platebracket 62 receives bolt 54, which also is received by through-hole 108 of indexer plate 50, andthrough-hole 124 of plate bracket 66 receives bolt 58, as shown in the assembly drawing of Fig. 5.Through-hole 122 and through-hole 106 receives another bolt 130 (see Fig. 19), thus fixedlymounting both the plate bracket 62 and the indexer plate to the slide rail 10 (discussed below). Platebracket 66 of the opposite side of the snowmobile is likewise fixed to the slide rail, but without anindexer plate. The plate brackets 62, 66 provide support between the coupling blocks 46, 48 and theslide rail 10. That is, the brackets 62, 66 pass forces seen by the coupler system (when, for example,the lower arm 62 is urged against coupling blocks 46, 48) to the slide rails, which are made ofaluminum. Because they are designed to carry stress, the plate brackets 62, 66 are preferably madeof 3/16″ brass plate. However, it will be understood to those skilled in the art that the thickness or11

CA 02358154 2001-10-03material used is not intended to be limiting, and that other materials and/or thicknesses can be usedas long as the combination selected is sufficiently strong and rigid.Refernng now to Figs. 16-20, the components of the upgrade kit 40 described above areconstructed and arranged to be assembled and attached to the slide rails 10 of a coupled snowmobilesuspension system. More specifically, upgrade kit 40 is configured to be assembled onto a Polaris~snowmobile suspension system of the type which is generally depicted, without the upgrade kit 40attached, in Figs. 1-4. Even more specifically, the upgrade kit 40 is configured to be assembledonto the Polaris~ XTRA-10 snowmobile suspension system, which is depicted in Figs. 16 and 17.As seen in Figs. 16 and 17 of the XTRA-10 model, the coupler block 30, rear stop 32, lower pivotarm 26, are slightly modified from the Polaris~ model shown in Figs. 1-4. The differences,however, are not substantial, so the same reference numerals are used for equivalent elements.Generally, the suspension system of the Polaris~ snowmobile includes a slide frame 13,which comprises a pair of laterally spaced apart slide rails 10 or longitudinal skids interconnectedtransversely on opposing lateral sides of the machine. The slide frame 13 is interconnected to thesnowmobile chassis 14 by a front and rear suspension arm, 12 and 20, respectively. As more clearlyseen in Fig. 17, each coupling block 30 is mounted to the slide rails 10 with bolts 126, and each rearstop 32 is mounted to the slide rails 10 with bolts 128. As discussed above and described in the‘579 patent, the lower pivot arm 26 can rotate within the limits defined by rear surface 31 of thefront adjuster block 30 and rear stop 32. The remainder of the suspension system is known in the artand described in the ‘579 patent, and therefore need not be described in detail.Referring now to Figs. 18 and 19, the attachment of upgrade kit 40 to the Polaris~suspension system will now be described. First, after raising and supporting the suspension off theground, the bolts 126 and 128, which mount adjuster blocks 30 and rear stop 32, are removed. The12

CA 02358154 2001-10-03adjuster blocks 30 are then removed from the slide rails 10. Then, after mounting the couplingblocks 46, 48 of the upgrade kit 40 to the rectangular portions 70, 72 of main shaft 42, the assemblyis installed so that coupling blocks 46, 48 replace the original blocks 30. The main shaft assembly(i.e., main shaft 42 and blocks 46, 48) is disposed on the inner side of the slide rails 10 (see Fig. 19).The indexer plate 50 is then inserted between adjuster block 48 (i.e., the block that containsthe ball spring plunger 90) and a slide rail 10 on one side of the snowmobile suspension. Through-hole 108 of indexer plate 50 is aligned with threaded hole 72 of main shaft 42, and through-hole 106is aligned with the mounting position of rear stop 32. The two plate brackets 62, 66 are theninstalled on the outside of the slide rails 10, with through-holes 124, 122 of each plate bracketaligned with the threaded holes of the main shaft 42 and the m~unting positions of each rear stop 32.Bolts 54 and 58 are then put in place, but not fully tightened, in order to retain the main shaft 42, theindexer plate 50, and the plate brackets 62, 66. The original rear stop 32 mounting bolts 128 arereplaced with longer bolts 130 (preferably 1 1/2 x 318 NC bolts with a nylon nut) and the rear stops32 are rebolted, joining together the indexer plate 50, the slide rail 10, and the plate brackets 62, 66.Bolts 54 and 58 are then tightened for complete installation of the upgrade kit 40. Preferably, atorque of 400 in-lb is applied to bolt 54. If a limiter strap 132 is used in the suspension system, it isdisposed below the main shaft 42, as shown in Fig. 18. Also, bolts 54 and 58 are preferably notthreaded over the entire length of the bolt. Rather, the portion of the bolts extending beyond thecoupling blocks 46, 48 after installation have smooth surfaces for rotationally sliding contact withthe indexer plate, slide rails, and support plates.A top view of the installed upgrade kit 40 is shown in Fig. 19. As seen, when the assemblyis installed and tightened, a side of the coupling blocks 48 and 46 for engagement with surface 27 ofarm 26 (see solid line in Fig. 20) is initially chosen and the ball of plunger 90 corresponds with and13

CA 02358154 2001-10-03is disposed within a hole (either bore 112, 114, 116, or 118) of the index bracket 50. Afterinstallation and the indexer plate 50 and coupling block 48 are engaged, a small gap 136, orclearance, exists between block 48, with indexer plate disposed in contiguous relation with the ballspring plunger’s 90 collar. Also, in the preferred embodiment, axial clearances 138, 140 remainbetween the head of bolts 54 and 58 and the support plates 62 and 66, respectively, after the boltsare completely tightened (i.e., bottomed-out in bores 78) to the upgrade kit 40. These clearances138, 140 permit the coupling blocks 46, 48 to easily rotate when adjusting the coupling blocks,discussed below.To adjust the coupling blocks 46, 48 so that a different side engages surface 27 of lowerpivot arm 26, a torque is applied to bolt 54 in the clockwise direction, as shown in Fig. 20. Sincethis torque further tightens bolt 54 and bolt 54 has already bottomed-out in bores 78, the appliedtorque is transmitted to and causes the main shaft 42 and coupling blocks 46, 48 to rotate clockwise.As torque is applied to the bolt 54, the ball 96 is compressed inward of plunger 90 and forced out ofthe hole of the indexer plate 50. When enough rotation is effected so that ball 96 « f nds » the nexthole in the indexer plate 50, the ball again springs into engagement with the indexer plate to preventfurther rotation of the adjuster blocks 46, 48. This process is repeated until the desired couplingblock side (i.e., either side 84, 85, 86, or 87 (Fig. 9)) is in position to engage surface 27 of arm 26,shown as dotted lines Fig. 20.The upgrade kit 40 of the present invention thus allows a quick and easy means to adjust thecoupler of the Polaris~ snowmobile. As originally manufactured, the rider had to first loosen thecentral mounting bolt 126. Then the rider had to, either with his fingers or with the aid of anothertool, rotate block 30 to the desired location, and then retighten the central mounting bolt 126. Therider had to then repeat these steps for the adjuster block on the opposite slide rail. With the14

CA 02358154 2001-10-03upgrade kit 40 installed, however, the rider only needs to perform a single step, which is to rotatebolt 54 clockwise with a suitable tool until the desired side of coupling blocks 46, 48 are in position.Notably, no loosening of the system is required, and no further tightening is required once the desirecoupling block side for engagement with surface 27 is in position. The ball plunger’s 90engagement with indexer plate 50 prevents further rotation of the adjuster blocks without the needto further tighten bolts 54 or 58. This allows the rider the ability to quickly and easily adjust thecoupling of the suspension for varying terrain conditions. Furthermore, the head of bolt 54 ispreferably sized to accommodate a conventional spark-plug wrench. Thus, the rider, who typicallyakeady carnes a spark-plug wrench when riding the snowmobile, need not bring an additional toolin order to make a coupling adjustment in the field.Though not intended to be limiting, the dimensions of the components of upgrade kit 5,which are sized for the Polaris~ XTRA-10 snowmobile suspension, are the following: Table 1: Dimensions of upgrade kit 40 components. Main Shaft 42 (Fig.dimension (inches)6)

L1 8.468

L2 2.250

L3 1.000

D 1 0.500

D2 0.900

Coupling blocks 46, 48 (Figs. 7 and 8) L4 1.656

L5 1.988

L6 0.750

L7 0.750

15

CA 02358154 2001-10-03 Lg 0.475

L9 0.344

L 10 1.000

Rl 0.750

R2 0.500

R3 0.375

R4 0.500

Indexer plate 50 (Fig. 14) L11 3.741

D4 0.375

DS 0.265

D6 0.395

RS 1.000

Plate brackets 62, 66 (Fig. 14) L12 3.741 D7 0.394 D8 0.375Although the upgrade kit 40 with the above dimensions is intended for the Polaris~ XTRA-snowmobile, the dimensions of the components above can be modified to fit the followingPolaris~ models: the STORM series (model years 1996-98); the STORM SE series (year 1997); the800 XCR series (model years 1999-2001); the XCR, XC, XCR SP, and XCR SE series (model years1996-2000), but excluding the 440 cc XCR, XC, and XC DELUXE models; the XC SP (modelyears 1999-2000); the ULTRA SPX and SPX SE series (model year 1997); the INDY XLT series(model year 1997); the INDY XCF (model year 1997-99); the INDY XLT Special (model year1998-99); the INDY 440 and 500 (model year 1996-1999); the INDY SUPER SPORT series (modelyear 1996-2000); the INDY TRAIL (model year 1996-99); and the INDY TRIUMPH (model year16

CA 02358154 2001-10-032000). However, as would be understood by those skilled in the art, there are potentially othersnowmobile suspensions on which the present invention may be used.In the preferred embodiment, the upgrade kit 40 is referred to as an after-market add-onapparatus that can be purchased and installed onto the snowmobile. However, it is alsocontemplated that the manufacturer may install the components of the upgrade kit 40, or equivalentcomponents, prior to the sale of the snowmobile. Therefore, the upgrade kit 40 is intended to referto the components of the kit 40 described herein above, regardless of whether the components areinstalled by the manufacturer prior to sale of the snowmobile, or whether the kit 40 is installed as anafter-market add-on.For example, the upgrade kit 40 can be installed onto a snowmobile 140 shown in Fig. 21.Snowmobile 140, as generally known in the art, is shown having a forward end 143 and a rearwardend 145 (that are defined consistently with the travel direction of the vehicle). Snowmobile 140includes a body 147 (i.e., the exterior upper portions) and a chassis 14. While not shown in FIG. 21,an engine is carried by chassis 14 at its forward end. In addition, two skis 141 are attached to theforward end of chassis 14 through a front suspension 149. An endless, drive track 146 of the rearsuspension 148 is disposed under chassis 14 and is connected operatively to the engine forpropulsion of the vehicle.At the front of chassis 14, snowmobile 140 includes fairings 145 that enclose the engine toprotect it and to provide a external shell that can be decorated so that the snowmobile isaesthetically pleasing. Typically fairings 145 comprise a hood and a bottom pad (neither of whichhave been individually identified in the Figures). A windshield 150 may be connected to fairings145 near the forward end 143 of snowmobile 140. Windshield 1 SO acts as a windscreen to lessenthe force of the air on a rider when snowmobile 10 is moving. A seat 152 extends from rearward17

CA 02358154 2001-10-03end 145 of snowmobile 140 to the fairings 145. A steering device 154, such as a handlebar, ispositioned forward of the rider and behind the engine. Two footrests (not shown) are positioned oneither side of seat 152 to accommodate the rider’s feet.While the invention has been described in connection with what is presently considered to bethe most practical and preferred embodiments, it is to be understood that the invention is not to belimited to the disclosed embodiments and elements, but, to the contrary, is intended to cover variousmodifications, combinations of features, equivalent arrangements, and equivalent elements includedwithin the spirit and scope of the appended claims. Furthermore, the dimensions of features ofvarious components provided are not meant to be limiting, and the size of the components can varyfrom the size that is portrayed in the figures and table herein in order to accommodate differentlysized suspension system components.18

1. An upgrade kit for a coupled snowmobile suspension, the upgrade kit comprising:a shaft having an axis of rotation;a pair of coupling blocks, each adapted to be fixedly connected relative to the axis ofrotation at each end of said shaft so that a torque on said shaft will be transmitted to said couplingblocks, said blocks having a plurality of sides corresponding to a plurality of positions of saidcoupling blocks, each of said sides being located at a different distance from said axis when saidcoupling blocks are connected to said shaft; andan indexer plate adapted to engage one of said coupling blocks in a selected one ofsaid positions of said coupling blocks,wherein the shaft is constructed and arranged to be mounted between a longitudinalpair of slide rails of the snowmobile suspension,wherein the coupling blocks are adapted to be rotated about said axis to therebyadjust the coupling of the snowmobile.

2. An upgrade kit according to claim 1, wherein said indexer plate includes a firstthrough-hole at one end and a second through hole at another end.

3. An upgrade kit according to claim 2, wherein one of said coupling blocks comprisesa resiliently biased protrusion for engagement with said indexer plate.

19

4. An upgrade kit according to claim 3, wherein said indexer plate further includes aplurality of equally spaced apart depressions for engagement with said protrusion, said first through-hole being centrally located of said plurality of depressions.

5. An upgrade kit according to claim 4, wherein said depressions are bores.

6. An upgrade kit according to claim 2, wherein said index plate comprises a resilientlybiased protrusion for engagement with one of said coupling blocks.

7. An upgrade kit according to claim 6, wherein one of said coupling blocks furtherincludes a plurality of equally spaced apart depressions for engagement with said protrusion, saidaxis of said shaft being centrally located of said depressions.

8. An upgrade kit according to claim 6, wherein said depressions are bores.

9. An upgrade kit according to claim 1, further comprising a pair of bolts to be insertedinto through-holes formed in said slide rails for mounting said shaft at each end to said slide rails,said shaft adapted at each end to receive said bolts.

10. An upgrade kit according to claim 1, wherein said shaft and said coupling blocks areintegrally formed.20

11. An upgrade kit according to claim 1, wherein said plurality of sides of said couplingblocks comprises four sides.

12. An upgrade kit according to claim 1, wherein said coupling blocks are made of ultrahigh molecular weight plastic.

13. An upgrade kit according to claim 1, wherein said shaft is made of aluminum.

14. An upgrade kit according to claim 1, wherein said indexer plate, when installed ontothe snowmobile suspension, is to be disposed between one of said coupler blocks and one of saidslide rails.

15. An upgrade kit according to claim 3, wherein said protrusion comprises a resilientlybiased ball mounted within a bore included by said coupling blocks.

16. An upgrade kit according to claim 9, further comprising a pair of plate bracketshaving one end including a through-hole therein for receiving one of said pair of bolts for attachingplate brackets to said slide rail and an other end including a through-hole therein for receiving asecond bolt for attachment to said slide rails.

17. An upgrade kit according to claim 9, wherein rotation of said shaft and said couplingblocks is to be performed by applying a torque to one of said pair of bolts.21

18. An upgrade kit according to claim 17, wherein said torque is applied in a directionwhich tightens said one of said pair of bolts.

19. A snowmobile, comprising:a chassis;an engine disposed on the chassis;an endless track disposed below the chassis and connected operatively to the enginefor propulsion of the snowmobile;at least one ski disposed on the chassis;a seat disposed on the chassis, suitable for a rider;a steering device disposed on the chassis forward of the seat, the steering devicebeing operatively connected to the at least one ski for steering the snowmobile;a slide frame for engagement with the endless track, said slide frame comprising alongitudinal pair of laterally spaced apart slide rails;a shaft having an axis of rotation;a pair of coupling blocks, each fixedly connected relative to the axis of rotation ateach end of said shaft so that a torque on said shaft will be transmitted to said coupling blocks, saidblocks having a plurality of sides corresponding to a plurality of positions of said coupling blocks,each of said sides being located at a different distance from said axis when said coupling blocks areconnected to said shaft; andan indexer plate adapted to engage one of said coupling blocks in a selected one ofsaid positions of said coupling blocks,22

wherein the shaft is mounted between said slide rails,wherein the coupling blocks are adapted to be rotated about said axis to therebyadjust the coupling of the snowmobile.

20. A snowmobile according to claim 19, wherein said indexer plate includes a firstthrough-hole at one end and a second through hole at another end.

21. A snowmobile according to claim 20, wherein one of said coupling blocks comprisesa resiliently biased protrusion for engagement with said indexer plate.

22. A snowmobile according to claim 21, wherein said indexer plate further includes aplurality of equally spaced apart depressions for engagement with said protrusion, said first through-hole being centrally located of said plurality of depressions.

23. A snowmobile according to claim 22, wherein said depressions are bores.

24. A snowmobile according to claim 20, wherein said index plate comprises aresiliently biased protrusion for engagement with one of said coupling blocks.

25. A snowmobile according to claim 24, wherein one of said coupling blocks furtherincludes a plurality of equally spaced apart depressions for engagement with said protrusion, saidaxis of said shaft being centrally located of said depressions.

23

26. A snowmobile according to claim 24, wherein said depressions are bores.

27. A snowmobile according to claim 19, further comprising a pair of bolts to be insertedinto through-holes formed in said slide rails for mounting said shaft at each end to said slide rails,said shaft adapted at each end to receive said bolts.

28. A snowmobile according to claim 19, wherein said shaft and said coupling blocks areintegrally formed.

29. A snowmobile according to claim 19, wherein said plurality of sides of said couplingblocks comprises four sides.

30. A snowmobile according to claim 19, wherein said coupling blocks are made of ultrahigh molecular weight plastic.

31. A snowmobile according to claim 19, wherein said shaft is made of aluminum.

32. A snowmobile according to claim 19, wherein said indexer plate, when installed ontothe snowmobile suspension, is to be disposed between one of said coupler blocks and one of saidslide rails.

33. A snowmobile according to claim 21, wherein said protrusion comprises a resilientlybiased ball mounted within a bore included by said coupling blocks.24

34. A snowmobile according to claim 27, further comprising a pair of plate bracketshaving one end including a through-hole therein for receiving one of said pair of bolts for attachingplate brackets to said slide rail and an other end including a through-hole therein for receiving asecond bolt for attachment to said slide rails.

35. A snowmobile according to claim 27, wherein rotation of said shaft and saidcoupling blocks is to be performed by applying a torque to one of said pair of bolts.

36. A snowmobile according to claim 35, wherein said torque is applied in a directionwhich tightens said one of said pair of bolts.25